Catheter spine assembly with closely-spaced bipole microelectrodes

ABSTRACT

An electrophysiologic catheter with a distal electrode assembly carrying very closely-spaced bipole microelectrodes on a plurality of divergent spines that can flexibly spread over tissue surface area minimized detection of undesirable noise, including far-field signals. Each spine has a flexible microelectrode panel having a substrate, at least one pair of microelectrodes, a trace for each microelectrode, and a soldering pad. Adjacent microelectrodes of a bipole pair are separated by a space gap distance ranging between about 50-300 microns. Each microelectrode may have a width of about 200 or 300 microns.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of and claims priority to and thebenefit of U.S. patent application Ser. No. 15/912,505 filed Mar. 5,2018, issued as U.S. Pat. No. 10,327,658, which is a continuation of andclaims priority to and the benefit of U.S. patent application Ser. No.15/018,810 filed Feb. 8, 2016, now U.S. Pat. No. 9,907,480, the entirecontents of which are incorporated herein by reference.

FIELD OF INVENTION

This invention relates to an electrophysiologic catheter, in particular,a cardiac electrophysiologic catheter with an electrode configurationthat provides for more accurate and discrete sensing of fractionatedsignals.

BACKGROUND

Electrode catheters have been in common use in medical practice for manyyears. They are used to stimulate and map electrical activity in theheart and to ablate sites of aberrant electrical activity.

In use, the electrode catheter is inserted into a major vein or artery,e.g., femoral artery, and then guided into the chamber of the heartwhich is of concern. Once the catheter is positioned within the heart,the location of aberrant electrical activity within the heart is thenlocated.

One location technique involves an electrophysiological mappingprocedure whereby the electrical signals emanating from the conductiveendocardial tissues are systematically monitored and a map is created ofthose signals. By analyzing that map, the physician can identify theinterfering electrical pathway. A conventional method for mapping theelectrical signals from conductive heart tissue is to percutaneouslyintroduce an electrophysiology catheter (electrode catheter) havingmapping electrodes mounted on its distal extremity. The catheter ismaneuvered to place these electrodes in contact with the endocardium. Bymonitoring the electrical signals at the endocardium, aberrantconductive tissue sites responsible for the arrhythmia can bepinpointed.

For sensing by ring electrodes mounted on a catheter, lead wirestransmitting signals from the ring electrodes are electrically connectedto a suitable connector in the distal end of the catheter controlhandle, which is electrically connected to an ECG monitoring systemand/or a suitable 3-D electrophysiologic (EP) mapping system, forexample, CARTO, CARTO XP or CARTO 3, available from Biosense Webster,Inc. of Irwindale, Calif.

The closely-spaced electrode pairs allow for more accurate detection ofnear-field potentials versus far-field signals, which can be veryimportant when trying to treat specific areas of the heart. For example,near-field pulmonary vein potentials are very small signals whereas theatria, located very close to the pulmonary vein, provides much largersignals. Accordingly, even when the catheter is placed in the region ofa pulmonary vein, it can be difficult for the electrophysiologist todetermine whether the signal is a small, close potential (from thepulmonary vein) or a larger, farther potential (from the atria).Closely-spaced bipoles permit the physician to more accurately removefar field signals and obtain a more accurate reading of electricalactivity in the local tissue. Accordingly, by having closely-spacedelectrodes, one is able to target exactly the locations of myocardialtissue that have pulmonary vein potentials and therefore allows theclinician to deliver therapy to the specific tissue. Moreover, theclosely-spaced electrodes allow the physician to determine the exactanatomical location of the ostium/ostia by the electrical signal.

However, manufacturing and assembling catheters with closely andprecisely spaced ring electrodes pose many challenges. Accuracy andconsistency in spacing between adjacent electrodes become critical tocatheter manufacturing and assembly. Conventional methods often useadhesives such as polyurethane to seal each ring electrode, whichcreates a margin between adjacent electrode or electrode pairs that canlimit how closely the electrodes can be spaced from each other.Typically, spacing of 1.0 mm or larger between electrode pairs can beachieved using such conventional methods. However, spacing smaller,especially 0.2 or 0.1 mm spacing is difficult to achieve. With suchsmaller spacing, there is the risk of adjacent electrodes coming incontact due to electrode tolerance specification or shifting ofelectrodes during assembly when medical grade adhesive such asPolyurethane is applied or when medical epoxy is curing.

Moreover, the conventional methods of attaching a lead wire to a ringelectrode also typically require spacing tolerances between adjacentring electrodes. Such attachment methods often result in an acute angleat which the lead wire must extend to reach the ring electrode which cancause stress leading to detachment or breakage.

Flexible electronics, also known as flex circuits, is a technology forassembling electronic circuits by mounting electronic devices onflexible plastic substrates, such as polyimide, PEEK or transparentconductive polyester film. Additionally, flex circuits can be screenprinted silver circuits on polyester. Flexible printed circuits (FPC)are made with a photolithographic technology. An alternative way ofmaking flexible foil circuits or flexible flat cables (FFCs) islaminating very thin (0.07 mm) copper strips in between two layers ofPET. These PET layers, typically 0.05 mm thick, are coated with anadhesive which is thermosetting, and will be activated during thelamination process. Single-sided flexible circuits have a singleconductor layer made of either a metal or conductive (metal filled)polymer on a flexible dielectric film. Component termination featuresare accessible only from one side. Holes may be formed in the base filmto allow component leads to pass through for interconnection, normallyby soldering.

Accordingly, a need exists for an electrophysiological catheter withbipole microelectrode pairs that are very closely spaced to minimizedetection of noise and/or far-field signals. There is also a need for amethod of manufacture and assembly of such a catheter wherein very closespacing between electrodes can be achieved readily and consistently withimproved precision and accuracy.

SUMMARY OF THE INVENTION

The present invention is directed to an electrophysiologic catheter witha distal electrode assembly carrying very closely-spaced bipolemicroelectrodes on a plurality of divergent spines that can flexiblyspread over tissue surface area for simultaneously detecting signals atmultiple locations with minimized detection of undesirable noise,including far-field signals.

In some embodiments, the catheter includes an elongated body and adistal electrode assembly having at least one spine with a flexiblemicroelectrode panel. The spine has a free distal end, and the panel hasa substrate conforming to an outer surface of the spine, at least onepair of microelectrodes, a trace for each microelectrode, and asoldering pad for each microelectrode, wherein each trace electricallycouples a respective microelectrode and a respective soldering pad.

In some detailed embodiments, adjacent microelectrodes of a bipole pairare separated by a space gap distance of about 300 microns or less. Insome detailed embodiments, the space gap distance ranges between about50 and 100 microns. In some detailed embodiments, the space gap distanceis about 50 microns.

In some detailed embodiments, each microelectrode has a width of about300 microns.

In some detailed embodiments, each microelectrode has an enlargedportion configured to cover a trace electrical connection.

In some detailed embodiments, each spine has a circular cross-section.

In some detailed embodiments, each spine has a rectangularcross-section.

In other embodiments, the catheter has an elongated body, and a distalelectrode assembly having a plurality of divergent spines, and aflexible panel on at least one spine, wherein the panel has a substrateconforming to an outer surface of the spine, a pair of microelectrodes,and a trace electrically coupling a respective microelectrode and arespective soldering pad, and wherein the pair of microelectrodes are atleast partially circumferentially wrapped around the spine, andmicroelectrodes of the pair are separated by a space gap distanceranging between about 50-200 microns.

In detailed embodiments, the spine has a planar surface configured tocontact tissue surface, and the pair of microelectrodes are positionedon the planar surface.

In detailed embodiments, the entirety of the pair of microelectrodes iswithin the planar surface.

In detailed embodiments, each microelectrode has a width ranging betweenabout 50-200 microns.

In additional embodiments, the catheter has an elongated body, and adistal electrode assembly having a plurality of spines, each spinehaving a free distal end and a preformed inward curvature toward alongitudinal axis of the assembly, and a flexible panel on at least onespine, the panel having a substrate conforming to an outer surface ofthe spine, a pair of microelectrodes, and a trace electrically couplinga respective microelectrode and a respective soldering pad, wherein thepair of microelectrodes are at least partially circumferentially wrappedaround the spine, and microelectrodes of the pair are separated by aspace gap distance ranging between about 50-300 microns.

In some detailed embodiments, the flexible panel has a longitudinalportion, at least a distal lateral portion, and a proximal base portion,wherein the trace is positioned in the longitudinal portion, the pair ofmicroelectrodes are positioned in the distal lateral portion and thesoldering pad is positioned in the distal base portion.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings. It isunderstood that selected structures and features have not been shown incertain drawings so as to provide better viewing of the remainingstructures and features.

FIG. 1 is a side view of a catheter of the present invention, accordingto an embodiment.

FIG. 2 is an end cross-sectional view of a catheter body of the catheterof FIG. 1, taken along line 2-2.

FIG. 3 is an end cross-sectional view of a deflection section of thecatheter of FIG. 1, taken along line 3-3.

FIG. 4 is a perspective view of a junction between the deflectionsection and a distal electrode assembly of a catheter of the presentinvention, according to an embodiment, with parts broken away.

FIG. 5 is a perspective view of a distal electrode assembly of thepresent invention, according to an embodiment.

FIG. 6 is a detailed view of a flexible microelectrode panel and a spineduring assembly, according to an embodiment.

FIG. 7 is a partial exploded perspective view of a flexiblemicroelectrode panel, according to an embodiment.

FIG. 8 is a side view of a distal electrode assembly of FIG. 5 incontact with tissue surface.

FIG. 9 is a detailed view of a spine with a flexible microelectrodepanel, according to another embodiment.

FIG. 10 is a side view of a distal electrode assembly in contact withtissue surface, according to another embodiment.

FIG. 11 is a partial exploded perspective view of a distal electrodeassembly with spines in accordance with the embodiment of FIG. 9.

FIG. 12A, FIGS. 12B, 12C and 12D are top plan views of arrangements ofmicroelectrodes according to different embodiments.

FIG. 13 is a detailed view of a spine support member in accordance withone embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, in some embodiment of present invention, a catheter10 includes a catheter body 12, an intermediate deflection section 14, adistal electrode assembly 15, and a control handle 16 proximal of thecatheter body 12. The distal electrode assembly 15 includes a pluralityof spines 42, each spine carrying at least one pair of closely-spacedbipole microelectrodes 85, wherein the microelectrodes of a pair has aseparation space gap distance therebetween of no greater than about 200microns.

In some embodiments, the catheter body 12 comprises an elongated tubularconstruction, having a single, axial or central lumen 18, as shown inFIG. 2. The catheter body 12 is flexible, i.e., bendable, butsubstantially non-compressible along its length. The catheter body 12can be of any suitable construction and made of any suitable material. Apresently preferred construction comprises an outer wall 17 made of apolyurethane, or PEBAX. The outer wall 17 comprises an imbedded braidedmesh of high-strength steel, stainless steel or the like to increasetorsional stiffness of the catheter body 12 so that, when the controlhandle 16 is rotated, the deflection section 14 of the catheter 10 willrotate in a corresponding manner.

The outer diameter of the catheter body 12 is not critical, but ispreferably no more than about 8 french, more preferably about 7 french.Likewise the thickness of the outer wall 17 is not critical, but is thinenough so that the central lumen 18 can accommodate components,including, for example, one or more puller wires, electrode lead wires,irrigation tubing, and any other wires and/or cables. The inner surfaceof the outer wall 17 is lined with a stiffening tube 20, which can bemade of any suitable material, such as polyimide or nylon. Thestiffening tube 20, along with the braided outer wall 17, providesimproved torsional stability while at the same time minimizing the wallthickness of the catheter, thus maximizing the diameter of the centrallumen 18. The outer diameter of the stiffening tube 20 is about the sameas or slightly smaller than the inner diameter of the outer wall 17.Polyimide tubing is presently preferred for the stiffening tube 20because it may be very thin walled while still providing very goodstiffness. This maximizes the diameter of the central lumen 18 withoutsacrificing strength and stiffness. As would be recognized by oneskilled in the art, the catheter body construction can be modified asdesired. For example, the stiffening tube can be eliminated.

In some embodiments, the intermediate deflection section comprises ashorter section of tubing 19, which as shown in FIG. 3, has multiplelumens, for example, off-axis lumens 21, 22, 23 and 24 and on axis lumen25. In some embodiments, the tubing 19 is made of a suitable non-toxicmaterial more flexible than the catheter body 12. A suitable materialfor the tubing 19 is braided polyurethane, i.e., polyurethane with anembedded mesh of braided high-strength steel, stainless steel or thelike. The outer diameter of the deflection section 14 is similar to thatof the catheter body 12. The size of the lumens is not critical and canvary depending on the specific application.

Various components extend through the catheter 10. In some embodiments,the components include lead wires 30 the distal electrode assembly 15,one or more puller wires 32A and 32B for deflecting the deflectionsection 14, a cable 34 for an electromagnetic position sensor 36 housedat or near a distal end of the deflection section 14, and a guidewiretubing 38. These components pass through the central lumen 18 of thecatheter body 12, as shown in FIG. 2.

In the deflection section 14, different components pass throughdifferent lumens of the tubing 19 as shown in FIG. 3. In someembodiments, the lead wires 30 pass through first lumen 21, the firstpuller wire 32A passes through second lumen 32, the guidewire tubing 38passes through third lumen 23, the cable 34 passes through fourth lumen24, and the second puller 34B passes through fifth lumen 25. The secondand fourth lumens 22 and 24 are diametrically opposite of each other toprovide bi-directional deflection of the intermediate deflection section14.

Distal of the deflection section 14 is the distal electrode assembly 15which includes a mounting stem 46 in the form of a short tubing mountedon a distal end of the tubing 19 of the intermediate deflection section14. (In that regard, it is understood that where the catheter 10 iswithout a deflection section 14, the mounting stem 46 is mounted on adistal end of the catheter body 12.) The stem 46 has a central lumen 48to house various components. The intermediate section 14 and stem 46 areattached by glue or the like. The stem 46 may be constructed of anysuitable material, including nitinol. As shown in FIG. 4, the stem 46houses various components, including the electromagnetic position sensor36, and a distal anchor for the puller wires 32A and 32B.

In the disclosed embodiment, the distal anchor includes one or morewashers, for example, a distal washer 50D and a proximal washer 50P,each of which has a plurality of through-holes that allow passage ofcomponents between the deflection section 14 and the stem 46 whilemaintaining axial alignment of these components relative to alongitudinal axis 40 of the catheter 10. The through-holes include holes52 and 54 that are axially aligned with the second and fourth lumens 22and 24 of the tubing 19, respectively, to receive a distal end of pullerwires 32A and 32B, respectively. It is understood that the puller wiresmay form a single tensile member with a distal U-bend section thatpasses through the holes 52 and 54. With tension on the washers 50D and50P exerted by the U-bend section of the puller wires, the washersfirmly and fixedly abut against the distal end of the tubing 19 of thedeflection section 14 to distally anchor the U-bend section.

Each washer includes through-hole 51 which is axially aligned with thefirst lumen 21 and allows passage of the lead wires 30 from thedeflection section 14 and into the lumen 48 of the stem 46. Each washeralso includes through-hole 55 which is axially aligned with the fifthlumen 25 of the tubing 19 and allows passage of the sensor cable 34 fromthe deflection section 14 into lumen 48 of the stem 46 where theelectromagnetic position sensor 36 is housed. Each washer furtherincludes on-axis through-hole 53 which is axially aligned with the thirdlumen 23 and allows passage of the guidewire tubing 38 from thedeflection section 14 and into the lumen 48 of the stem 45. Marker bandsor ring electrodes 27 may be carried on the outer surface of thecatheter at or near the near the distal end of the intermediatedeflection section 14, as known in the art.

As shown in FIG. 4, extending from the distal end of the stem 46 areelongated spines 42 of the distal electrode assembly 15. Each spine hasa support member 43, a non-conductive covering 44 that extends along theeach spine 42. Each spine has a proximal portion that extends proximallyinto the lumen 48 of the stem 46. The non-conductive coverings 44 of thespines may also extend proximally into the lumen 48. Each spine 42 maybe arranged uniformly about the distal opening of the stem 46 inequi-radial distance from adjacent spines 42. For example, with fivespines, each spine may be spaced apart at about 72 degrees from adjacentspines. Suitable adhesive, e.g., polyurethane, may be used to pot andanchor the proximal ends of the spines 42 and their nonconductivecoverings 44. The suitable adhesive seals the distal end of the stem 46,which is formed to leave open the distal end of the guidewire tubing 38.

Each spine support member 43 is made of a material having shape-memory,i.e., that can be temporarily straightened or bent out of its originalshape upon exertion of a force and is capable of substantially returningto its original shape in the absence or removal of the force. Onesuitable material for the support member is a nickel/titanium alloy.Such alloys typically comprise about 55% nickel and 45% titanium, butmay comprise from about 54% to about 57% nickel with the balance beingtitanium. A nickel/titanium alloy is nitinol, which has excellent shapememory, together with ductility, strength, corrosion resistance,electrical resistivity and temperature stability. The non-conductivecovering 44 can be made of any suitable material, and is preferably madeof a biocompatible plastic such as polyurethane or PEBAX.

Lead wires 30 for microelectrodes 85 carried on the spines 42 extendthrough the catheter body 12 and the deflection section 14 protected bya nonconductive sheath 60. Toward the distal electrode assembly 15, thelead wires 30 extend through a polytube 68, as shown in FIG. 4. The leadwires 30 diverge at the distal end of the polytube 68, and extend towardtheir respective spine 42

As shown in FIG. 5 and FIG. 6, each spine 42 includes a flexiblemicroelectrode member in the form of a panel 80 that is affixed to theouter surface of spine 42, conforming to the shape of the spine 42. Theflexible electrode panel 80, as better shown in FIG. 7, includes abiocompatible flexible plastic substrate 81 constructed of a suitablematerial, for example, polyimide or PEEK, at least one pair ofclose-spaced microelectrodes 85, separated therebetween by a gap spaceS.

In some embodiments, the substrate 81 is generally elongated with alongitudinal (thinner “T”) portion 82, at least one distal lateral(wider “W”) portion 83 traversing the longitudinal portion 82 at agenerally perpendicular angle, and a proximal (less wide “LW”) baseportion 84 having a slightly greater lateral dimension than thelongitudinal portion 82 (T, W and LW shown in FIG. 7). The longitudinalportion 82 is configured to extend along the length of a spine 42 andthe lateral portion 83 is configured to wrap circumferentially around adistal portion of the spine 42. The base portion 84 is positioned on aproximal end portion of the spine 42 and is thus protected within thelumen 48 of the mounting stem 46. On the base portion 84 are solderingpatches 88, one for each lead wire 30 whose distal end is soldered to arespective soldering patch 88. The soldering patches 88 are thereforeprotected and insulated within the lumen 48 of the mounting stem 46. Itis understood that only one spine member 42 is shown in FIG. 4 forpurposes of clarity, and that the polytube 68 may be sized appropriatelyto receive the proximal ends of all spine members 42 extending from thetubing 19, where, in some embodiments of the present invention, theplurality of spine members 42 may range between about two and eight.

In other embodiment, the most proximal longitudinal portion 82 may besignificantly elongated such that the base portion 84 is located furtherproximally in the deflection section 14, the catheter body 12, or evenin the control handle 16, as appropriate or desired.

On an outer surface of each lateral portion 83, a respective pair ofthin, elongated microelectrodes 85 (microelectrode strips) are affixedor otherwise provided in alignment with the lateral portion 83 so thateach microelectrode generally forms a ring microelectrode R (FIG. 6)when the lateral portion 83 is wrapped circumferentially around thespine 42. It is understood that the longitudinal portion 82 may be aswide as the lateral portion 83 although the amount of surface areacoverage and/or thickness of the substrate affects the flexibility ofthe spine 42.

In some embodiments, the space gap distance S separating eachmicroelectrode of a pair ranges between about 50 and 300 microns. Insome embodiments, the space gap distance ranges between about 100-200microns. In some embodiments, the space gap distance is about 50microns. Moreover, in some embodiments, each microelectrode itself mayhave a width W ranging between about 50-100 microns. At least one pairof closely-spaced bipole microelectrodes 85 are provided on each spine42. In the illustrated embodiment, each spine carries four pairs ofbipole pairs for a total of eight microelectrodes.

In some embodiments, a panel 80 has a length of about 8.0 cm, whereinthe longitudinal portion 82 has a length of about 5.0 cm and a width nogreater than about 1.0 mm, and the base portion 84 has a length of about3.0 cm and a width of about 1.2 mm. Each pair of microelectrodes isspaced apart from an adjacent pair of microelectrodes by a distance ofabout 5.0 mm, with each microelectrode having a width of about 50microns, and a length of about 2.56 mm.

In some embodiments, the substrate 81 comprises multiple layers, forexample, first or outer layer 81 a, second or middle layer 81 b, andthird or inner layer 81 c, each having a first surface 91 and a secondsurface 92. It is understood that the letters “a”, “b” and “c” designatecorresponding features in the layers 81 a, 81 b and 81 c of thesubstrate 81. The microelectrodes 85 are applied to or otherwisedeposited on the first surface 91 a of the outer layer 81 a, to overliethrough-holes 86 a which are formed in the layer 81 a to provideconnection access for electrical traces 87 b that extend along the firstsurface 91 b of the longitudinal portion 82 b of the second layer 81 bbetween corresponding microelectrodes 85 and soldering pads 88 carriedon the second surface 92 c of the base portion 84 c of the third layer81 c. Additional traces 87 c run along the first surface 91 c of thethird layer 81 c. Through-holes 86 b, 89 b (not shown) and 89 c areformed in the layers 81 b and 81 c to provide connection access for theelectrical traces 87 b and 87 c to more proximal microelectrodes 85, andmore proximal soldering pads (not shown in FIG. 7). It is understoodthat the plurality of layers 81 depends on the amount of surface andspace available thereon to accommodate the plurality of traces 87connecting the microelectrodes 85 and the soldering pads 88. It is alsounderstood that with increasing layers flexibility of the spines can bereduced. Thus, the plurality of layers to accommodate the plurality ofmicroelectrodes is balanced against the flexibility of the spines whichenable conformity to tissue surface but decreases with increasingsubstrate thickness. In the illustrated embodiment of FIG. 7, thesubstrate 81 has three layers with each layer 81 carrying four traces.It is understood that there is one corresponding trace 87 and onecorresponding soldering pad 88 for each microelectrode 85. Each leadwire 30 is soldered to a corresponding soldering pad. In that regard, itis also understood that the traces may be arranged differently, indifferent patterns and/or on different layers, as needed or appropriate.

As shown in FIG. 5 and FIG. 6, the substrate 81 is affixed to thenonconductive covering 44 of the spine 42 with the longitudinal portion82 extending longitudinally along the spine 42 and the lateral portions83 wrapped circumferentially around the spine 42. In that regard, thelateral dimension or width W of the lateral portions 83, and moresignificantly of the microelectrodes 85, is comparable to thecircumference of the spine 42 such that opposing ends 85E of themicroelectrodes can reach each other or at least come in close contactto generally form and function as ring microelectrodes R carried on thespine 42. In the illustrated embodiment of FIG. 5, the substrate 81 isaffixed to the forward-facing or distal side of the spine that isadapted to contact tissue, although it is understood that the placementside of the substrate is less critical where the microelectrodes arelong enough to wrap around the spine. In another embodiment discussedfurther below, placement side is more critical where the lateraldimension W is adjusted and decreased as desired or appropriate forlesser circumferential reach around the spine 42.

As shown in FIG. 5, each spine 42 is preformed with a slight inwardcurvature such that the distal electrode assembly 15 has a generallyslightly concave configuration resembling an open umbrella. Thispreformed configuration enables each spine 42 to engage tissue surface93 generally along its entire length when catheter is advanced distallyagainst tissue surface, as shown in FIG. 8. Without the preformedconfiguration, the distal electrode assembly 15 may tend to flipoutwardly (much like an umbrella flipping inside out under strong wind)and lose tissue contact as the catheter is pushed distally againsttissue surface.

As FIG. 8 illustrates, ends 85E of microelectrodes may not be in contactwith tissue surface which exposes the microelectrodes to detectingundesirable noise, for example, far-field signals. Accordingly, FIG. 9and FIG. 11 illustrate distal electrode assembly 117 of an alternateembodiment which provides a greater planar surface for tissue contactthat minimizes exposure of the microelectrodes to noise and far-fieldsignals. It is understood that similar components between the distalelectrode assembly 17 and distal electrode assembly 117 are designatedby similar reference numbers for ease of discussion herein.

Whereas the spine 42 of FIG. 6 has a more circular cross-section, spine142 of FIG. 9 has a more rectangular cross section which provides thegreater planar surface 100 on which flexible microelectrode member inthe form of panel 180 can be selectively applied or affixed.Advantageously, the entirety of the microelectrodes 185 (including theirends 180E) is confined to the surface area of the planar surface 100 andtherefore generally the entirety of microelectrodes 185 is in contactwith tissue when the planar surface 100 is in contact with tissue 193,as shown in FIG. 10.

Support member 143 has a rectangular cross-section which is adopted byheat-shrink nonconductive covering 144 to provide the greater planarsurface 100. In some embodiments, the panel 180 as shown in FIG. 11 hassubstrate 181, microelectrodes 185, traces 187 and soldering pads 188(not shown) having similar construction as their counterparts describedabove for panel 80. The substrate 181 comprises multiple layers, forexample, first or outer layer 181 a, second or middle layer 181 b, andthird or inner layer 181 c, each having a first surface 191 and a secondsurface 192. However, as one difference, the substrate 181 is devoid oflateral portions, with a longitudinal portion 182 having a lateraldimension W that is comparable or at least no greater than the lateraldimension of the planar surface 100 so that the substrate 181 remainsconfined on the planar surface 100. The microelectrodes 185 areelongated and thin. To achieve a minimum space gap S between adjacentmicroelectrodes 185 of a pair while accommodating through-holes 186,microelectrodes 185 have enlarged portions or ends 189, as shown in FIG.11, that are sized larger than the through-holes 186 to span and overliethe through-holes 186 so that traces 187 b and 187 c can be connected tothe microelectrodes 185. In one embodiment, the microelectrode has awidth of about 50 microns and the enlarged portion 189 has a width ofabout 100 microns.

The enlarged portion or end 189 of a microelectrode may extend to theright (forming a “right-handed microelectrode” 185R) or to the left(forming a “left-handed microelectrode” 185L), as shown in FIG. 11. Apair may comprise a right-handed microelectrode 185R and a left handedmicroelectrode 185L, as shown in FIG. 11, or two right-handedmicroelectrodes 185R-185R, as shown in FIG. 12B and FIG. 12C, or twoleft-handed microelectrodes 185L-185L, as shown in FIG. 12A and FIG.12D. The microelectrodes of a pair may be arranged in any formation,including, for example, a mirrored pairs (FIG. 11), as upside down pairs(FIG. 12A, FIG. 12B, FIG. 12C, and FIG. 12D), as side-by-side pairs(FIG. 11, FIG. 12A and FIG. 12B), or as stacked pairs (FIG. 12C and FIG.12D). In any case, the enlarged portions ends are turned outwardly awayfrom each other so that the space gap distance as defined betweenadjacent linear edges can be minimized.

As described above in relation to FIG. 7, the microelectrodes 185 ofFIG. 9 and FIG. 11 are similarly affixed to the front surface 191 a ofthe longitudinal portion 182 a of the first layer 181 a, and solderingpads 188 are affixed to the second surface 192 c of the base portion 184c of the third layer 181 c. Traces 187 b and 187 c run along the secondand third layers 181 b and 181 c, respectively. Through-holes 186 a, 189b and 189 c are formed in the layers 181 a, 181 b and 181 c,respectively, to provide the traces with connection access to themicroelectrodes 185 and the soldering pads 188 (not shown). Again, it isunderstood that the plurality of layers 181 depends on the amount ofsurface and space available thereon to accommodate the plurality oftraces 187 connecting the microelectrodes 185 and the soldering pads188, which accommodation is balanced against the desired flexibility ofthe spine 142 with the understanding that increasing thickness of thesubstrate can decrease the flexibility of the spine 42. In theillustrated embodiments of FIG. 9 and FIG. 11, each layer 181accommodates four traces for a total of eight traces servicing eightmicroelectrodes and eight soldering pads.

With each spine 142 preformed with a slight inward curvature such thatthe distal electrode assembly 115 has a generally slightly concaveconfiguration resembling an open umbrella, the planar surface 100 andthe microelectrodes 185 thereon can fully engage and make contact withtissue surface so as to minimize exposure of the microelectrodes tonoise and far-field signals without flipping inside out, as shown inFIG. 8. The substrate 181 is selectively affixed to the forward-facingor distal side of the spine 142 where the planar surface 100 is adaptedto contact tissue surface with minimal exposure of the microelectrodes185 to noise and far-field signals.

Distal electrode assembly 115 having spines 142 with a rectangularcross-section wherein the X dimension along the planar surface 100 isgreater than the Y dimension perpendicularly thereto, as shown in FIG.9, is also particularly adapted for minimizing kinking and stress to thespines at their area of greatest flexion or divergence D (see FIG. 10)located slightly distal of the distal end of stem 146.

It is understood that as the need or desire arises, any given spine maycarry one or more flexible electrode panel of the same or differentembodiments, as described above.

In some embodiments, the spine support members 43/143 are formed from asingle elongated hollow cylinder or tube 90, as shown in FIG. 13, withan intact proximal cylindrical portion 102 (which may form the stem46/146 of the distal electrode assembly), and a distal portion 104 withformed elongated extensions or fingers 106 that function as theplurality of support members 43, separated by space gaps therebetweenthat are formed by longitudinal cuts in the sidewall of the cylinder 90,or by removal, e.g., laser cutting, of elongated longitudinal strips 105from the sidewall of cylinder 90. Each finger 106 is shaped to divergeor splay outward at or near its proximal end and to have a slight inwardcurvature, as shown in FIG. 5.

In the depicted embodiment, the lead wires 30 extending through thecentral lumen 18 of the catheter body 12 and the first lumen 21 in thedeflection section 14 may be enclosed within a protective sheath 60 toprevent contact with other components in the catheter. The protectivesheath 60 may be made of any suitable material, preferably polyimide. Aswould be recognized by one skilled in the art, the protective sheath canbe eliminated if desired.

The microelectrodes 85 can be made of any suitable solid conductivematerial, such as platinum or gold, preferably a combination of platinumand iridium. The closely-spaced microelectrode pairs allow for moreaccurate detection of near field pulmonary vein potential versus farfield atrial signals, which is very useful when trying to treat atrialfibrillation. Specifically, the near field pulmonary vein potentials arevery small signals whereas the atria, located very close to thepulmonary vein, provides much larger signals. Accordingly, even when themapping array is placed in the region of a pulmonary vein, it can bedifficult for the physician to determine whether the signal is a small,close potential (from the pulmonary vein) or a larger, farther potential(from the atria). Closely-spaced bipole microelectrodes permit thephysician to more accurately determine whether he/she is looking at aclose signal or a far signal. Accordingly, by having closely-spacedmicroelectrodes, one is able to better target the locations ofmyocardial tissue that have pulmonary vein potentials and thereforeallows the clinician to deliver therapy to the specific tissue.Moreover, the closely-spaced microelectrodes allow the physician tobetter determine the anatomical location of the ostium/ostia by theelectrical signal.

As described above, the electromagnetic position sensor 36 is housed inthe lumen 48 of the stem 46, as shown in FIG. 4. The sensor cable 34extends from a proximal end of the position sensor, via through-hole 55(not shown) of the washers 50D and 50P, the fifth lumen 25 of the tubing19 of the deflection section 14 (see FIG. 3), and the central lumen 18of the catheter body 12 (see FIG. 2). The cable 34 is attached to a PCboard in the control handle 16, as known in the art. In someembodiments, one or more distal electromagnetic position sensors may behoused in the distal electrode assembly, for example, in one or moredistal portions of the spines 42.

As shown in FIG. 3 and FIG. 4, the puller wires 32A and 32B (whether astwo separate tensile members or parts of a single tensile member) areprovided for bi-directional deflection of the intermediate section 14.The puller wires are actuated by mechanisms in the control handle 16that are responsive to a thumb control knob or a deflection control knob11 (see FIG. 1). Suitable control handles are disclosed in U.S. Pat.Nos. 6,123,699; 6,171,277; 6,183,435; 6,183,463; 6,198,974; 6,210,407and 6,267,746, the entire disclosures of which are incorporated hereinby reference. The puller wires 32A and 32B extend through the centrallumen 18 of the catheter body 12 (see FIG. 2) and through the second andfourth lumens 22 and 24, respectively, of the tubing 19 of thedeflection section 14 (see FIG. 3). They extend through holes 52 and 54,respectively of the washers 50D and 50P (see FIG. 4). Where the pullerwires are part of a single tensile member, the single tensile member hasa U-bend at the distal face of the distal washer 50D which anchors thedistal ends of the puller wires. In that regard, the U-bend extendsthrough a short protective tubing 70. Alternatively, where the pullerwires are separate tensile members, their distal ends may be anchoredvia T-bars, as known in the art and described in, for example, U.S. Pat.No. 8,603,069, the entire content of which is incorporated herein byreference. In any case, the puller wires may be made of any suitablemetal, such as stainless steel or Nitinol, and each is preferably coatedwith TEFLON or the like. The coating imparts lubricity to the pullerwires. The puller wires preferably have a diameter ranging from about0.006 to about 0.010 inch.

A compression coil 66 is situated within the central lumen 18 of thecatheter body 12 in surrounding relation to each puller wire 32A and32B, as shown in FIG. 3. Each compression coil 66 extends from theproximal end of the catheter body 12 to the proximal end of theintermediate section 14. The compression coils 66 are made of anysuitable metal, preferably stainless steel. Each compression coil 66 istightly wound on itself to provide flexibility, i.e., bending, but toresist compression. The inner diameter of the compression coil 66 ispreferably slightly larger than the diameter of its puller wire. TheTEFLON coating on each puller wire allows it to slide freely within itscompression coil.

The compression coil 66 is anchored at its proximal end to the outerwall 17 of the catheter body 12 by a proximal glue joint (not shown) andat its distal end to the intermediate section 14 by a distal glue joint(not shown). Both glue joints may comprise polyurethane glue or thelike. The glue may be applied by means of a syringe or the like througha hole made the sidewalls of the catheter body 12 and the tubing 19.Such a hole may be formed, for example, by a needle or the like thatpunctures the sidewalls which are heated sufficiently to form apermanent hole. The glue is then introduced through the hole to theouter surface of the compression coil 66 and wicks around the outercircumference to form a glue joint about the entire circumference of thecompression coil.

Within the second and fourth lumens 22 and 24 of the intermediatesection 14, each puller wire 32A and 32B extends through a plastic,preferably TEFLON, puller wire sheath 39 (FIG. 3), which prevents thepuller wires from cutting into the sidewall of the tubing 19 of thedeflection section 14 when the deflection section 14 is deflected.

The preceding description has been presented with reference to presentlypreferred embodiments of the invention. Workers skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes in the described structure may be practicedwithout meaningfully departing from the principal, spirit and scope ofthis invention. Any feature or structure disclosed in one embodiment maybe incorporated in lieu of or in addition to other features of any otherembodiments, as needed or appropriate. It is understood that a featureof the present invention is applicable to multiplying linear motion of apuller wire, contraction wire, or any other object requiring insertion,removal, or tensioning within a medical device, including the disclosedelectrophysiology catheter. As understood by one of ordinary skill inthe art, the drawings are not necessarily to scale. Accordingly, theforegoing description should not be read as pertaining only to theprecise structures described and illustrated in the accompanyingdrawings, but rather should be read consistent with and as support tothe following claims which are to have their fullest and fair scope.

What is claimed is:
 1. An electrophysiological catheter comprising: anelongated body; a distal electrode assembly comprising: a plurality ofspines, each of the spines having a free distal end and a proximal endextending from a distal end of the elongated body, each of the spineshaving a surface area; and at least one pair of microelectrodes, themicroelectrodes of the at least one pair of microelectrodes beinglocated on the surface area of the spine, and the microelectrodes of theat least one pair of microelectrodes being separated by a space gapdistance of about 50 to 300 microns.
 2. The catheter of claim 1, whereineach microelectrode of the at least one pair of microelectrodes has awidth ranging between about 50-300 microns.
 3. The catheter of claim 1,wherein the distal electrode assembly further comprises a flexible panelon at least one of the spines, the flexible panel comprising: asubstrate conforming to the surface of its respective spine, thesubstrate comprising: a longitudinal portion configured to extendgenerally along a length of its respective spine, at least one distallateral portion generally traversing the longitudinal portion, and aproximal base portion proximal of the longitudinal portion, the at leastone pair of microelectrodes being on the at least one distal lateralportion of the substrate, a soldering pad for each of themicroelectrodes, each of the soldering pads being located on theproximal base portion of the substrate, and a trace for each of themicroelectrodes, each of the traces electrically coupling a respectiveone of the microelectrodes on the at least one distal lateral portion ofthe substrate and a respective one of the soldering pads on the proximalbase portion of the substrate.
 4. The catheter of claim 3, wherein thelongitudinal portion of the substrate has a width that is thinner than awidth of the proximal base portion of the substrate.
 5. The catheter ofclaim 3, wherein the at least one distal lateral portion of thesubstrate has a width greater than a width of the longitudinal portionand a width of the proximal base portion.
 6. The catheter of claim 5,wherein the proximal base portion of the substrate has a width that isgreater than a width of the longitudinal portion.
 7. The catheter ofclaim 3, wherein the at least one distal lateral portion of thesubstrate is configured to wrap generally circumferentially around atleast a portion of the respective spine.
 8. The catheter of claim 7,wherein the microelectrodes of the at least one pair of microelectrodesextend laterally on the at least one distal lateral portion of theirrespective spine such that each of the microelectrodes generally forms aring microelectrode when the respective distal lateral portion iswrapped generally circumferentially around the portion of the respectivespine.
 9. The catheter of claim 3, wherein the longitudinal portion ofthe substrate has an elongated proximal-most region connecting theproximal base portion to a proximal-most one of the at least one distallateral portion.
 10. The catheter of claim 3, wherein the at least onedistal lateral portion of the substrate comprises a plurality of distallateral portions, and the at least one pair of microelectrodes comprisesa plurality of pairs of microelectrodes, and each of the plurality ofpairs of microelectrodes is located on a respective one of the distallateral portions of the substrate.
 11. The catheter of claim 10, whereinthe plurality of distal lateral portions of the substrate comprises fourdistal lateral portions, the plurality of pairs of microelectrodescomprises four pairs of microelectrodes, and each of the four pairs ofmicroelectrodes is located on a respective one of the four distallateral portions of the substrate.
 12. The catheter of claim 3, whereinthe proximal base portion of the substrate and the soldering pads foreach of the microelectrodes of the at least one pair of microelectrodesare located in the elongated body.
 13. An electrophysiological cathetercomprising: an elongated body; a distal electrode assembly comprising: aplurality of spines, each spine having a free distal end and a proximalend extending from a distal end of the elongated body; and a flexiblepanel on at least one of the spines, the flexible panel comprising: asubstrate conforming to an outer surface of its respective spine, thesubstrate comprising a plurality of layers, a pair of microelectrodes, atrace for each of the microelectrodes, and a soldering pad for each ofthe microelectrodes, each trace electrically coupling a respective oneof the microelectrodes and a respective one of the soldering pads. 14.The catheter of claim 13, wherein the plurality of layers of thesubstrate comprises three layers.
 15. The catheter of claim 14, whereinthe three layers of the substrate comprise an outer layer, an innerlayer, and a middle layer between the outer layer and the inner layer,the pair of microelectrodes is located on the outer layer, the trace foreach of the microelectrodes is located on the middle layer, and thesoldering pad for each of the microelectrodes is located on the innerlayer.
 16. The catheter of claim 15, wherein the outer layer has aplurality of through holes, each of the through holes configured toallow connection of each of the traces on the middle layer to theirrespective one of the pair of microelectrodes on the outer layer. 17.The catheter of claim 15, wherein the middle layer has a plurality ofthrough holes, each of the through holes configured to allow connectionof each of the traces on the middle layer to their respective one of thesoldering pads on the inner layer.
 18. The catheter of claim 13, whereinthe substrate further comprises: a longitudinal portion configured toextend generally along a length of its respective spine, a distallateral portion generally traversing the longitudinal portion, the pairof microelectrodes being located on the distal lateral portion, and aproximal base portion proximal of the longitudinal portion, the tracefor each of the microelectrodes being located on the proximal baseportion.
 19. The catheter of claim 18, wherein the distal lateralportion of the substrate is configured to wrap generallycircumferentially around at least a portion of the respective spine. 20.The catheter of claim 18, wherein the distal lateral portion of thesubstrate comprises a plurality of distal lateral portions, and the pairof microelectrodes comprises a plurality of pairs of microelectrodes,and each of the plurality of pairs of microelectrodes is located on arespective one of the distal lateral portions of the substrate.